Tertiary alkylation utilizing an admixture of olefins and tertiary alkyl chlorides

ABSTRACT

Benzene or naphthalene is selectively tertiary alkylated by reaction with C7 to C44 tertiary alkyl chlorides in admixture with tertiary olefins similar to those from which the tertiary alkyl chlorides are derived, in the presence of a Friedel-Crafts catalyst and under reaction conditions including a temperature from -20* C. to 30* C., a pressure of from 5 to 400 mm Hg. absolute and in the presence of a rapidly boiling liquid.

United States Patent Boggs 51 May 18, 1972 TERTIARY ALKYLATION UTILIZINGAN ADMIXTURE OF OLEFINS AND TERTIARY ALKYL CHLORIDES Inventor: Jesse K.Boggs, Houston, Tex.

Assignee:

Filed:

App]. No.:

Esso Research and Engineering Company Dec. 28, 1970 US. Cl. ..260/671 R,260/671 B, 260/671 P Int. Cl ..C07c 3/56 Field of Search ..260/67.l R,671 B, 671 G, 671 P References Cited UNITED STATES PATENTS Schlatter..260/67l R 2,880,250 3/1959 Myerson eta] ..260/67l B PrimaryExaminerCurtis R. Davis AnorneyThomas B. McCulloch, Melvin F. Fincke,John S. Schneider, Sylvester W. Brock, Jr. and Timothy L. BurgessABSTRACT Benzene or naphthalene is selectively tertiary alkylated byreaction with C, to C tertiary alkyl chlorides in admixture 10 Claims,No Drawings TERTIARY ALKYLATION UTILIZING AN ADMIXTURE F OLEFINS ANDTERTIARY ALKYL CHLORIDES CROSS-REFERENCE TO RELATED APPLICATION Thesubject matter of the present invention is related to that described inmy copending application, Ser. No. 101,921, filed on Dec. 28, 1970, andentitled Selective Tertiary Alkylation of Aromatic Hydrocarbons," thedisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION 1 Field of the Invention This inventionrelates to the Friedel-Crafts catalyzed alkylation of benzene ornaphthalene to produce a tertiary alkyl substituent thereon. Thereaction is carried out with an admixture of tertiary alkyl chloridesand the internal isoolefins from which the tertiary alkyl chloride isderived.

2. Description of the Prior Art Alkyl benzenes have been recognized asdesirable compounds for various uses. There is much prior art relatingto the production of alkyl benzenes generally, and some of the prior artrelates to the production of alkyl benzenes containing small tertiaryalkyl groups (such as t-butyl benzene). However, when utilizing abulkier tertiary alkylgroup, in order to obtain a heavier oil fordifferent uses, it has been found that it is very difficult to obtainapreferential tertiary alkylation reaction. As described in my copendingapplication referred to above, the reaction of tertiary alkyl chlorideswith aromatics such as benzene yields hydrochloric acid which builds upin concentration within the liquid phase and, after a certain level hasbeen reached, the HCl promotes isomerization of the tertiary alkylchloride into a secondary alkyl chloride which then reacts with benzene,producing the less desirable secondary alkylated product. The secondaryalkylated product, unlike the tertiary alkylated product, possesses avulnerable hydrogen atom on the alkyl carbon attached to the benzenering. This vulnerable hydrogen atom causes reactions leading to theformation of sludge and other undesirable degradation when the oil isused under conditions of thermal or oxidative load.

DISCUSSION OF THE PRESENT INVENTION ry alkyl substituent of sufficientsize to provide the desired physical properties to the resultantcompound, it has been found to be difficult to carry out a reactionwhich yields the tertiary substituent as a selective product. Asdisclosed in my copending application, Ser. No. 101,921, referred toabove, selective tertiary alkylation can be accomplished by carrying outthe reaction under a vacuum and in the presence of a boiling liquid, soas to remove the evolved HCl from the reaction zone rapidly enough toprevent its concentration in the liquid phase from exceeding theacceptable maximum. It has also been found that the selective alkylationreaction required the use of the tertiary alkyl halide and not atertiary olefin alone. Surprisingly, and according to the presentinvention, an admixture of tertiary olefins with the tertiary alkylhalide derived therefrom can be used successfully in the selectivetertiary alkylation of benzene. It is believed that, under the reactionconditions employed in the alkylation reaction, the evolved hydrogenhalide reacts in situ with the isoolefin which is present to formadditional tertiary alkyl halide, which is then utilized in theselective alkylation reaction. The olefin is thus operative to helpreduce the concentration of free hydrogen halide in the liquid phase.

Since the desired characteristics of the oil are dependent on the typeof tertiary alkyl substituent which is employed, the isoolefins whichare used will be those internal olefins which, upon reaction withhydrogen halide, yield the desired tertiary alkyl halide.

THE PROCESS The alkylation process is more specifically described in mycopending application above referred to, the disclosure thereof beingincorporated hereinto by reference. In general, it relates to thediscovery that, by uu'lizing a vacuum and a boiling liquid in thealkylation reaction zone, selective tertiary alkylation of aromatichydrocarbons can be accomplished. It has been found that, by using thecombination of a substantially 'subatmospheric pressure and a boilingliquid, the hydrogen halide which is evolved from the alkylationreaction is rapidly swept from the liquid phase into the vapor phaseabove the reaction mass and is removed from the reaction zone before asubstantial concentration of hydrogen halide can build up in the liquidreaction mass. The hydrogen halide concentration in the liquid reactionmass is maintained below a concentration level which varies according tothe catalyst employed, the tertiary alkyl halide, and the aromaticnucleus. The catalyst is the most important variable: for benzenealkylation, the hydrogen halide concentration must be kept below 0.02mol fraction if FeCl is the catalyst, and below 0.005 if AlCl is thecatalyst. The mol fraction is calculated on the basis of the liquidreaction mass as disclosed in the aforesaid copending application.

Reaction temperatures are chosen to allow the reaction of the bulkytertiary alkyl halide with the aromatic nucleus. Inasmuch as thetertiary alkyl halide may contain from seven to 44 carbon atoms, thereaction takes place slowly at extremely low temperatures. Therefore,the reaction is carried out at a temperature from about 20 C. to about30 C., preferably from 1520 C. The pressure is maintained at a suitablylow level, in order to establish boiling conditions within the liquidmass. The pressure therefore will be coordinated with the temperature ofthe liquid which is to boil. Suitably the pressure will range from 5 mmHg. to 400 mm Hg. absolute, preferably from 5 to mm Hg. absolute. Wherebenzene is used as the aromatic nucleus, and is itself to supply theboiling liquid, the pressure will preferably be about 20-40 mm Hg.absolute, with a temperature range from l5'-20 C. being preferred.

The reaction is carried out in the presence of a Friedel- Craftscatalyst such as aluminum chloride or ferric chloride. The catalyst maybe maintained in solution in the alkyl chloride, may be maintained as aslurry phase solid, or as a fixed or fluidized bed, all of which isknown to the art. Preferably, the amount of catalyst to be used when itis in solution will range from about 0.005 to 0.1 mol/mol of mixedtertiary alkyl chloride and olefin of structures R RC=OHR or R(|)=CH2 AR originally charged to the reaction zone.

The residence time of the aromatic hydrocarbon within the reaction zonemay range from 5 to 500 minutes. A shorter reaction time will beemployed, along with an excess of benzene, where a monoalkylationreaction is desired. Contrarily, a longer reaction time and morealkylating agent will be employed where dialkylation is to beemphasized.

ALKYLATING AGENT The alkylating agent of the present invention is anadmixture of tertiary alkyl chlorides with the internal isoolefinshaving the structures of CH R from whence the chloride is derived. Thus,suitable tertiary alkyl chlorides (and isoolefin) may contain from sevento 44 carbon atoms, preferably from seven to 34 carbon atoms. Suitabletertiary alkyl halides, identified as chlorides, are 10-chloro-lO-rnethyl-eicosane, 6-chloro6-methylhexadecane, 2-chloro-2-methylhexane, 2-chloro-2-methylheptane, 2-chloro-2-methyloctane, 2, chloro-2-methylnonane, 2chloro-2- methyldecane,2-chloro-2-methylundecane, 2-chloro-2-mehtyldodecane,2-chloro-2-n-octyldecane, etc.

The synthetic lubricant product will have a better combination ofphysical properties (such as pour point, viscosity and viscosity index)if the alkylating agents are a mixture of different carbon numbers;e.g., for an average carbon number of about C the t-alkyl chlorides andtolefins may have varying carbon numbers such as C through CAlternatively, a single t-alkyl chloride may be employed with a mixtureof tertiary olefins.

The tertiary olefins will exhibit structures represented by theformulas:

where R represents alkyl substituents, preferably straight chained. Asaforesaid, the total number of carbon atoms in the olefin will be set bythe number desired in the t-alkyl chloride, and will range from seven to40, preferably seven to 34, carbon atoms.

The corresponding internal isoolefins may be identical in structure tothe tertiary alkyl chloride, having instead of the chlorine atom anunsaturated linkage alpha to the carbon atom from which the branchedchain extends. For example, l-methyleicosene-9 and IO-methyleicosene-lOand 2-nonyldodecene-l correspond to lO-chloro-lO-methyleicosane, and6-methylhexadecene-5, 6-methylhexadecene-6 and 2-pentyldodecene-lcorrespond to 6-chloro-6-methylhexadecane. The relative proportionsbetween the isomeric olefins will depend upon the manner in which theywere obtained, and insofar as the present invention is concerned, willbe immaterial.

The ratio of the admixture of isoolefins to the tertiary alkyl halideis, however, important in that it must be maintained at a level wherethe reaction between evolved hydrogen halide and the isoolefin canprovide enough tertiary alkyl carbonium ions to replace those beingreacted with the aromatic nucleus. Therefore, the mol ratio ofisoolefins to tertiary alkyl halide should be from about 1:10 to about:1, preferably within the range from 1:3 to about 2:1.

The admixture of isoolefins and tertiary alkyl halide provides thealkylating agent. For monoalkyl products, the mol ratio of alkylatingagent to benzene or naphthalene-should range from about 1:40 to about5:1, preferably from 1:40 to about lzl; for increased amounts of dialkylproducts the ratio should be from about 1:2 to :1.

AROMATlC NUCLEUS The aromatic nucleus for use in the present process isbenzene or naphthalene and their lower alkyl derivatives such astoluene, xylenes, ethylbenzene and admixtures thereof. Preferably,substantially pure benzene, commonly called nitration grade, will beused, an example of which is shown Copper Corrosion No iridescence orgray or black discoloration Color 0.003 g. potassium dichromate in lliter H,O Solidifying Point (dry basis C), min. 5 C. Flash, Tag OpenCup, F. Water or suspended matter Absent However, commercial benzeneneed not be completely pure, but may contain small amounts of othercompounds, especially other aromatics in small proportions.

PRODUCT S The tertiary alkylated benzenes which are obtained from theprocess of the present invention may be used as lubricants, greases,hydraulic oils, etc., depending upon the viscosity and other physicalproperties of the product. Generally, the hydraulic oils and lubricatingoils will be monoalkylated products whereas the dialkylated productswill be used as the base stock for grease formulations. As an example ofa hydraulic oil produced by the present invention, see Table ll below.

Blended as follows: Synthetic oil, 98 wt. percent; Tricresyl phosphate,1 wt. percent; Antioxidant (ethyl 702), 1 wt. percent.

1 As determined by MIL-II-27G01A.

2 The finished blended oil may also contain VI improvcr and pourdepressants as desired.

By reference to Table ll it can be seen that the products of Examples 1and 2 have provided satisfactory aviation hydraulic fluids. Since theyare substantially pure compounds, the properties are controllable, andsince the substituents are tertiary alkyl groups, the compounds do notsuffer undue thermal and oxidative degradation under service and thosedesirable properties can be maintained.

In order to illustrate the present invention, the following examples aregiven:

EXAMPLE 1 Benzene was alkylated with a mixture of tri-substitutedethylene type C,, isoolefins and the corresponding tertiary alkylchlorides. The olefin mixture was made up of 34 mol percent ofl0-methyleicosene-9, 51 mol percent of lO-methyleicosene-lO, and 15 molpercent of 2-nonyldodecene-l:

2-nonyldodecene-i The tertiary alkyl chloride is derived from themixture of three olefins, and has the structure:

-ch1oro-, IO-methyleicosane An admixture of 239 g of the olefin mixtureand 258 g of the alkyl chloride plus 293 g of benzene was added to 293 gof benzene and 5 g of AlCl over a period of 60 minutes while stirringthe liquid reaction mass. The temperature varied from 5 C. to C. duringthe reaction period. A vacuum was maintained, the pressure during thereaction being about 60 mm Hg absolute. After termination of thereaction the product was recovered and found to have the followinganaly- SlSI tertiary alkyl benzene 64 secondary alkyl benzene 36 primaryalkyl benzene 0 The product was compounded to produce an AviationHydraulic Fluid having the characteristics shown in Table 11 above.

EXAMPLE 2 Benzene was alkylated with a mixture of internal C isoolefinsand the corresponding tertiary alkyl chloride. The olefin mixture wasmade up of 32 volume percent of 6-methylheiiadecene-S and 68 volumepercent of 6-methylhexadecene- 6:

The tertiary alkyl chloride is derived from both of the abovementionedolefins and has the structure:

An admixture of 139 g of the olefin mixture, 274 g. of the alkylchloride and 293 g of benzene was added as the alkylation agent to 293 gof benzene and S g of aluminum chloride over a period of 60 minuteswhile stirring the liquid reaction mass. The temperature varied from 5C. to 15 C. during the reaction period. A vacuum was maintained, thepressure during the reaction being about 60 mm Hg absolute. Aftertermination of the reaction, the product was recovered and found to havethe following analysis:

tertiary alkyl benzene 69 secondary alkyl benzene 31 primary alkylbenzene 0 The product was compounded to produce an aviation hydraulicfluid having the characteristics shown in Table 11 above.

Having disclosed my invention, what is to be covered by Letters Patentshould be determined from the following claims.

I claim:

1. A process of selectively tertiary alkylating an aromatic hydrocarbonchosen from the group consisting of benzene and naphthalene and thelower alkyl derivatives thereof which comprises:

in a reaction zone maintained at a pressure from about 5 mm Hg absoluteto about 400 mm Hg absolute and a temperature from about 20 C. to about30 C.

and in contact with a Friedel-Crafts catalyst which is present incatalytically effective amounts,

reacting said aromatic hydrocarbon with an admixture of isomericisoolefins, one or more having the structure where R is an alkyl group,and the tertiary alkyl chloride derived therefrom,

the mol ratio of isomeric olefins/tertiary alkyl chloride being fromabout 0.1:1.0 to about 5:1 and the benzene/alkylating agent mol ratiobeing from about 40:1 to 1:15, while said benzene is in a rapidlyboiling state.

2. A process in accordance with claim 1 wherein the isomericolefins/tertiary-alkyl chloride mol ratio is from about 1:3 to about 2:1.

3. A process in accordance with claim 1 wherein the described isomericolefins have C numbers from C to C and the t alkyl chloride has an equalor unequal carbon number.

4. A process in accordance with claim 3 wherein the aromatic hydrocarbonis benzene and the ratio of components range as follows:

olefin/tertiary-alkyl chloride is from 1:3 to 2:1 and benzene/alkylatingagent is from 20:1 to 1:8.

5. A process in accordance with claim 1 wherein the aromatic hydrocarbonis naphthalene or a tertiary alkyl substituted naphthalene.

6. A process in accordance with claim 5 wherein the described isomericolefinsltertiary-alkyl chloride mol ratio is from about 1:3 to 2:1.

7. A process in accordance with claim 1 wherein the described isomericolefins are of equal or different carbon numbers from the tertiary-alkylchlorides and both are in the range of seven to 44 carbon numbers.

8. A process in accordance with claim 7 wherein the aromatic hydrocarbonis benzene and the mo] ratios of the isomeric olefins/tertiary-alkylchloride is from 1:3 to 2:1 and benzene/alkylating agent is from 20:1 to1:8.

9. A process in accordance with claim I wherein the aromatic isnaphthalene or a tertiary-alkyl substituted naphthalene. Y

10. A process in accordance with claim 9 wherein the described isomericolefinsltertiary-alkyl chloride mol ratio is from about 1:3 to 2:1.

2. A process in accordance with claim 1 wherein the isomericolefins/tertiary-alkyl chloride mol ratio is from about 1:3 to about2:1.
 3. A process in accordance with claim 1 wherein the describedisomeric olefins have C numbers from C10 to C34 and the t-alkyl chloridehas an equal or unequal carbon number.
 4. A process in accordance withclaim 3 wherein the aromatic hydrocarbon is benzene and the ratio ofcomponents range as follows: olefin/tertiary-alkyl chloride is from 1:3to 2:1 and benzene/alkylating agent is from 20:1 to 1:8.
 5. A process inaccordance with claim 1 wherein the aromatic hydrocarbon is naphthaleneor a tertiary alkyl substituted naphthalene.
 6. A process in accordancewith claim 5 wherein the described isomeric olefins/tertiary-alkylchloride mol ratio is from about 1:3 to 2:1.
 7. A process in accordancewith claim 1 wherein the described isomeric olefins are of equal ordifferent carbon numbers from the tertiary-alkyl chlorides and both arein the range of seven to 44 carbon numbers.
 8. A process in accordancewith claim 7 wherein the aromatic hydrocarbon is benzene and the molratios of the isomeric olefins/tertiary-alkyl chloride is from 1:3 to2:1 and benzene/alkylating agent is from 20:1 to 1:8.
 9. A process inaccordance with claim 7 wherein the aromatic is naphthalene or atertiary-alkyl substituted naphthalene.
 10. A process in accordance withclaim 9 wherein the described isomeric olefins/tertiary-alkyl chloridemol ratio is from about 1:3 to 2:1.